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Unread 11-07-2011, 03:36 PM   #1
copleydad
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Timing after Nutter-What am I doing wrong?

Did the Nutter bypass 3 days ago. Before I started, I checked the timing with the idle at about 750rpm and it read 0 degrees, idling a bit rough so I figured the timing off had a lot to do with it (read somewhere normal factory setting is 6 BTDC with Carter - I have a new MC 2100).

Did the Nutter - orange to orange, purple to purple - and then set the timing to 8* BTDC as specified in EVERYTHING I read on this forum. Then, readjusted the idle to be 750rpm and test drove her without rechecking timing. She ran good, but kind of ran on when I shut her off. Rechecked the timing and it was around 12* BTDC, reset it to 8 and then had to re-readjust the idle to be at 750.

I moved the manifold vac to the dizzy to ported when I did the Nutter. I close off the vac line every time I reset the timing. I have re adjusted many times since the Nutter, so want to start all over again.

HOW do I initially set the timing? Every time I cheange the idle, the timing changes, and vice versa, so where and how do I start? There must be a "base" setting, I just don't know how to do it, have searched and googled, but all the info says is "set timing to 8* BTDC", but the idle changes everything.

So, my good fellow members, what am I being stoopid about? Would really like to get this girl hopping and running good without knocking or stuttering or spitting.

FYI - new plugs and dist cap and rotor, and pulled and rechecked plugs once.

Thanks for helping!

Bobby

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Unread 11-07-2011, 05:13 PM   #2
89yjsahara258
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I have the same setup as you do. I got the car running and set the idle to 680rpm and then adjusted the timing. I then readjusted the idle and proceeded to correct the timing. This time the idle stayed the same and I could move on to mixture. Every time I adjust my timing I fiddle with the idle after words and then double check the timing.

Just a thought but 750rpm might be too high for idle as the centrifugal advance weights might be advancing the timing which when the RPM drops on take off could be retarding your timing (weights retracting). Not a 100% on that but when I had an unrelated high idle issue before at 1100 rpm (different vehicle) the weights were active during initial timing but as soon as the rpm dropped my initial advance fell and I had performance issues.

Good luck,

Spencer
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Unread 11-07-2011, 05:27 PM   #3
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That may be my problem, rpm too high.

I have searched so many threads, I'm totally confused. Several threads say set idle to 1600 and set timing, some say 9 plus or minus BTDC at 700 where others say 13 and one said 3 BTDC at idle.

Figure I would like to get the timing right before I even think to mess with the mixture. Right now it's knocking when I hit the gas, so figure I need to retard it again (clockwise turn I believe), but she's gonna cough and sputter. I guess set idle to 680, retard dist, and raedjust idle to 680 and set timing to 8*BTDC, am I right? Every time I turn the dist, my idle changes, and I have the vac line blocked.

Is yours connected to ported vac or manifold vac?
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Unread 11-07-2011, 06:05 PM   #4
89yjsahara258
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According my Haynes manual without the computer connected advance should be between 9-11* BTDC. I got the 680 rpm from a buddies manual for a 302 which is what the MC2100 i have is off of so i figured it a good base line.

As far as the sputter goes are you getting backfire through the carb or just a bog down then it catches. On MC2100's the accelerator pump shot timing and size is adjustable on the front and driver side of the carb. The 4 pin holes near the linkage adjusts sooner (top) and later (bottom) and where that link connects to the pump there are two hole with the outside providing a smaller fuel shot and the inside providing a larger. It is pretty straight forward as it is all mechanical advantage.

The reason I explain this is that mine initially sputtered when I installed it but after playing with the shot timing it turned out the stutter was fuel starvation during acceleration.

Another check to do is for vacuum leaks. What did your carb come off of? Mine being from a 1973 Ford Maverick had a thermo climatic choke that is basically a huge VAC leak when not plugged from under the carb. When you step on the gas the ported vac (which I use for my distributor) increases but if you have a leak it will not advance the timing far enough.

Another spot to check it around the gasket. Are you using a really thick top gasket? Mine fit two ways on the adapter but one way pushed into the accelerator pump housing causing a vac leak but visually it looked fine. I also found that the gasket that came with my adapter that goes between the manifold and adaptor was not thick enough and was leaking so I replaced it with my stock thick Carter one and it fixed that problem.

You are right to start at 8* and continue to advance from their.

Sorry for the long response but I hope it helps get your runnin right,

Spencer

EDIT: The reason I understand to the 1600rpm timing adjustment is that the old MCU can only react to problems by retarding the timing (it can't see into the future) so you set the timing with the centrifugal advance weights fully advanced so that the computer can retard the timing from inputs using the knock sensor and the like. Without the computer you should time at idle like virtually all other pre smog cars.
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Unread 11-07-2011, 06:47 PM   #5
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Thanks Spencer. I'm gonna putz with the timing and idle in the morning when it gets light out again and see how she does on the way to work. Thanks, I'll post up how it goes.

Bobby
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Unread 11-08-2011, 02:02 PM   #6
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Looks like I got the timing right, runs at speed with no knocking or sputtering, but it still idles kinda rough.

Quote:
Originally Posted by 89yjsahara258 View Post

As far as the sputter goes are you getting backfire through the carb or just a bog down then it catches. On MC2100's the accelerator pump shot timing and size is adjustable on the front and driver side of the carb. The 4 pin holes near the linkage adjusts sooner (top) and later (bottom) and where that link connects to the pump there are two hole with the outside providing a smaller fuel shot and the inside providing a larger. It is pretty straight forward as it is all mechanical advantage.

The reason I explain this is that mine initially sputtered when I installed it but after playing with the shot timing it turned out the stutter was fuel starvation during acceleration..
Got the carb from that Ebay guy and had a buddy help me put it in. Took all the precautions for vac leaks, so pretty confident that's not an issue. Gonna go look for these pinholes on the carb for adjustment. How should these be adjusted? Is this where I've read to turn them in and back them out 3 turns? All of them?
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Unread 11-08-2011, 02:22 PM   #7
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For rough idle you are correct to adjust the two screws at the base. Start with three turns out it each and turn them equally in a half turn each until the rpm drops a bit. Then turn them out a half turn and begin tightening them 1/8 a turn until you have the same result and finish by undoing the screws 1/8 from the rpm drop. If your idle speed changes more than like 20 or 30 rpm reset the idle speed and start over.

The accelerator pump adjustment is more around a stutter under acceleration. The size of the shot adjustment is located above the idle screws and is a thick arm running perpendicular to the valve cover that has a thin shaft forming an L shape that ends beside the throttle linkage. On the end by the throttle linkage is where the 4 shot timing holes are located. Generally a good stating point is second hole from the top and the smaller fuel shot which is on the furthest outside hole.

A quick check I use for vac leaks is to spray some wd40 around the base and see if it gets sucked in. It is is worth a check because its easy to do and if there is it is likely the culprit.
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Unread 11-08-2011, 04:15 PM   #8
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Thanks Spencer. Try it tomorrow.
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Unread 11-11-2011, 02:30 PM   #9
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Well, I think I got it set. Runs so much better. Followed all your direction Spencer, but still felt I was doing something wrong. Found this while still searching around from forum member "Unfocused"....

"Rotate the dizzy counter-clockwise (advance) to find the highest vac on the gauge, then rotate the dizzy clockwise (retard) until the vac drops off about 4 inches. Repeat several times noting the absolute highest vac reading and back off. On the last cycle, advance to just touching the maximum vac, back off 1 inch of vac, and tighten the hold down bolt at the base of the dizzy. Your timing is now set to where your engine wants to be. You can now use the timing light to find out where it is happy. Reconnect anything you disconnected before."

So, went to Harbor Freight today to get cheap vacuum gauge, auto parts places wanted $25+++ (couldn't justify it). Found one for $14 and tried the above.

Before I started, I checked the timing with the light and it was right at 8* BTDC at 700rpm, and the vacuum nipple on the distributor was pointing at 4:00. Undid the vac lines to hook up the gauge and followed Unfocused's instructions, and found the maximum vacuum (21.5 in) minus one inch (20.5 in) had the vac nipple pointed at 3:00. So, rechecked and set idle to 700rpm and rechecked timing, and there she was at 8* BTDC, but the engine was running SO much better. Took her for a one exit test run on the highway and there was no knocking, great pickup and didn't seem like she was gonna die when I got off the next exit to come home.

I did check the needles in front of the carb, the 2 screws on the bottom. When I went to rest them all the way in, I counted the turns at 2 1/4 turns. Did everything you suggested Spencer, baby step turns in and out from 3 out, and the happiest point was still at 2 1/4 turns . The other holes you talk about, the shot holes, haven't been messed with yet, and don't know if I should. You say they are more for stutter on acceleration, but when I accelerate, the engine runs smooth.

She idles much better, although there is still a bit of a shimmy. I notice on the vacuum gauge when it was hooked up that the needle kinda jumped about 1/2 in, maybe 3/4, whenever the engine stumbled a bit. I checked all the vacuum lines going to/from the intake and carb by closing them off, and there was no change. So, thinking maybe a bad wire? A bad plug (even though they're new)? I took a can of carb cleaner (makes a noticeable stutter) with the red straw and checked all around the base and sides of the carb by spraying and there was no evidence of a leak anywhere there. (WD40? How do you tell if it's being "sucked in"?)

I sort of thought my new Energy Suspension motor mounts (the poly ones) were allowing a bit of shake, but after seeing the vacuum gauge, I ruled that out.

I'll be checking wires and plugs tomorrow (DAMN YOU DAYLIGHT SAVINGS), maybe pop off the wires and replace them "under warranty" from Auto Zone and take it from there, unless you think I should try something else. You seem much more knowledgeable than I about this, so I defer to you on this. Is my thinking re: plugs and wires sound? Any other ideas?

Thanks
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Unread 11-11-2011, 02:41 PM   #10
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Sorry, meant to say 680 rpm. When I look at where she idles from the dash tach, I just guesstimate it being 700. I used a tach under the hood doing all the timing stuff.
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Unread 11-11-2011, 04:30 PM   #11
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Glad you got the issue sorted out! If you have checked vac leaks then yes I would check the wires. You should also check the state of the contacts under the distributor cap and make sure that the rotor does not have any play aside from the mechanical advance which you will feel tension. How consistent is the shudder?

Spencer
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Unread 11-11-2011, 04:48 PM   #12
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New cap and rotor but will recheck. Also will grab a new set of wires tomorrow and should have a spare new set of plugs as well.

Yeah, it's pretty consistent. Figure at 700 rpm, that's about 11 - 12 rp second, and she stutters about 2 - 3 seconds, so maybe it is a bad plug or wire

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Unread 11-11-2011, 09:17 PM   #13
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Idle should be about 7-9*. Timing does not have anything to do with the carb. Now the timing as to do with the RPM and where it falls in the cycle of the rotation. Now once you have your timing set somewhere close then you start getting the carb adjusted. Then you have to fiddle back and forth just a little.
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Unread 11-13-2011, 01:02 PM   #14
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So, still trying to smooth out the idle. Pulled and checked routing of every vac line and made sure any vac hole is tubed or plugged.

Vac line from dist goes from it to ported vac on passenger side of carb. Tried connecting to manifold vac, no change at idle and seemed rougher at speed. So, switched back.

Seems to run great at throttle, just idling sux.

Found this in the box with the emissions guts when everything came off



image-433710412.jpg




image-1588915150.jpg

Tried it on the vac line with no change in idle. This valve is designed so air flows from carb side to dist side, so attached to ported vac would never draw air from dist under load and never draw air at idle if on manifold vac.

Maybe I'm just over thinking this. Maybe I'll go get a beer.
image-2266370656.jpg  
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Unread 11-13-2011, 01:13 PM   #15
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Can the coil make it idle rough? It is going on 23 years old, and she looks a bit haggard.
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